This application claims the benefit of Korean Application Nos. 99-48451, filed Nov. 3, 1999 and 00-15327, filed Mar. 25, 2000, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to optical recording/reproducing, and more particularly, to a physical identification data (PID) addressing method using a wobble signal, a wobble address encoding circuit, a method and circuit for detecting the wobble address, and a recording medium in a high density optical recording and reproducing system.
2. Description of the Related Art
Information used for physical location recognition to determine a location to which data is written on a disc in an optical recording and reproducing system is referred to as physical identification data (PID). Generally, PID is address information of a physical sector in a recording medium on which data is recorded in units of sectors. This is essential information for recording data at a certain location on a disc and finding the location at a later time.
In other words, PID indicates address information for finding a specified sector to record/reproduce data to/from a certain location, particularly in a recording/reproducing disc, and indicates address information of a sector which is pre-mastered during manufacture of a disc regardless of existence or non-existence of user data. Accordingly, PID is supposed to be resistant to errors and have a structure allowing fast detection in order to exactly and quickly find the location of a sector which data will be recorded on or reproduced from.
Various methods of recording PID on a disc can be largely classified into two methods. One method is recording physical location information on a disc by forming embossed pits in the same pattern as that used in a read-only optical disc to allow a certain location on the disc to be detected based on the embossed pits. The other method uses a wobble signal which can be obtained by giving some changes to recording tracks on a disc at a predetermined time interval.
An area, which is provided for performing PID addressing using the former method, that is, using embossed pre-pits, is referred to as a header field, as shown in FIG. 1. According to a digital versatile disc (DVD) specification for rewritable disc (2.6 or 4.7 gigabytes (GB) DVD-random access memory (RAM)) version 1.0, physical location information is recorded at the location of the so called header field, which is composed of pre-pits, during manufacture of a substrate. The header field includes a variable frequency oscillator (VFO) area for phase locked loop (PLL), a PID area to which a sector number is assigned, an ID error detection (IED) area for storing ID error detection information and a postamble (PA) area for synchronizing an initial phase for modulation of data recorded following the header field. In a PID addressing method using pre-pits, such a header field comprising embossed pre-pits is appropriately disposed at the start of a sector to allow a pickup to easily find and move to a desired location using this information. A sector number, sector type and a land track/groove track can be recognized from the addressed information, and even servo control is possible.
In such a PID addressing method using conventional embossed pre-pits, data cannot be recorded in areas in which pits are formed. Therefore, a problem of a decrease in recording density in proportion to the areas where the pits are formed occurs.
To store a large amount of data with a high density, it is necessary to increase a recordable area (a user data area) by decreasing a track pitch and minimizing a non-recordable area (overhead). For this purpose, it is effective to use a wobble signal.
When forming a substrate for a recording disc, grooves are formed along recording tracks on the substrate to allow a certain track to be exactly tracked by a pickup even if data is not recorded on the track. The portions other than the grooves are referred to as lands. Recording methods can be classified into a method of recording data on either a land or a groove and a method of recording data on both the land and the groove. It is more advantageous to use the land and groove recording method in which data is recorded on both the land and the groove as the density of data increases.
In addition, a method of generating a signal of a specified frequency by varying both walls of a groove to use it as an auxiliary clock signal during recording is used. This signal is referred to as a wobble signal. A wobble signal having a single frequency is also recorded in the substrate of a DVD-RAM disc.
In a PID addressing method using a wobble signal, overhead information such as a PID signal can be recorded by varying a wobble signal having a single frequency, for example, periodically varying the phase or frequency of the wobble signal, during recording. Here, the PID signal embedded in the wobble signal is generally referred to as a wobble address.
Since the conventional PID addressing method using a wobble signal uses the variation of both walls of a groove track in which a wobble will be recorded, as shown in FIG. 2, the method can be used only in discs employing a land recording method in which information is not recorded in groove tracks. In other words, when using changes in both walls of each groove track, address information of two groove tracks at both sides of a land track can be mixed with each other, so that exact information cannot be obtained from the land track. Accordingly, both the addresses of a land track and a groove track cannot be indicated just by using a wobble address formed in the groove track. Therefore, it is difficult to use the conventional method in discs employing a land and groove recording method in which information is recorded in both land and groove tracks.
Although a wobble address is recorded in the side wall of a groove track at the boundary between a land track and the groove track, information of wobbles formed in both walls of the land and groove tracks is simultaneously read when the land and groove recording method of recording information in land and groove tracks is used. Accordingly, a PID signal cannot be exactly recorded or detected when using the wobble addressing method shown in FIG. 2.
To solve this problem, a method of recording a wobble address in only one wall of each groove track is proposed, as shown in FIG. 3. In this wobble addressing method, however, since a wobble signal is generated from only one wall of a groove track, the strength of the signal decreases. In addition, since the same signal is read from the groove track and an adjacent land track, additional information for discriminating a land track from a groove track is required.
To solve the above problems, a first object of the present invention is to provide a new physical identification data (PID) addressing method using a wobble to solve an overhead problem of an addressing method using embossed pre-pits, and to solve a problem of a conventional wobble addressing method being incompatible with a land and groove recording method.
A second object of the present invention is to provide a PID addressing method in which a simple carrier wobble signal and phase-modulated wobble address information is time division multiplexed in both walls of either of the groove and land tracks using two beams.
A third object of the present invention is to provide a method of detecting address information from a simple carrier wobble signal and phase-modulated address information which is recorded in both walls of either of the groove and land tracks by way of time division multiplexing.
A fourth object of the present invention is to provide a wobble address encoding circuit for a high density optical disc recording and reproducing system.
A fifth object of the present invention is to provide a wobble address detecting circuit for a high density optical disc recording and reproducing system.
A sixth object of the present invention is to provide a recording medium in which a simple carrier wobble signal and phase-modulated address information, which is time division multiplexed, is recorded in both walls of either of the groove and land tracks.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
In order to achieve the above object, the present invention provides a method of addressing physical identification information using a wobble on an optical recording medium having land and groove tracks. The method includes alternately recording a simple wobble carrier and wobble address information on both walls of either of a groove track and a land track, the wobble address information being phase modulated with two phases having a maximum possible phase difference therebetween using the simple wobble carrier, wherein the simple wobble carrier is recorded in a section of an adjacent track corresponding to a section in which the wobble address information is recorded in a current track.
The present invention also provides a method of detecting a wobble address from an optical recording medium, in which a simple wobble carrier and address information, which is phase modulated with two phases having a maximum possible phase difference therebetween using the simple wobble carrier, are alternately recorded on both walls of either of a groove track and a land track, and the simple wobble carrier is recorded in a section of an adjacent track corresponding to a section in which the phase modulated address information is recorded in a current track, in an optical recording and reproducing system having an optical detecting device. The method includes recovering the wobble carrier from the sum of a sum signal and a push-pull signal of radially half-divided output signals of the optical detecting device, providing an output signal having an original signal component and a harmonic component by multiplying the push-pull signal by the wobble carrier, and removing the harmonic component from the output signal and demultiplexing the original signal component to recover land and groove address information.
The present invention also provides a circuit which encodes an address using a wobble in an optical recording and reproducing system. The circuit includes a generator which generates a wobble signal having only a simple carrier, a phase modulator for phase modulating land and groove address information indicating physical identification information with two phases of the wobble signal having the maximum possible phase difference, and a time division multiplexer which time division multiplexes the wobble signal and the phase modulated wobble address information in both walls of either of a groove track and a land track, at a predetermined time interval.
The present invention also provides a circuit for detecting a wobble address from an optical recording medium, in which a simple wobble carrier and address information, which is phase modulated with two phases having the maximum possible phase difference therebetween using the simple wobble carrier, are alternately recorded on both wall of either of a groove track and a land track, and the simple wobble carrier is recorded in a section of an adjacent track corresponding to a section in which the phase modulated address information is recorded in a current track, in an optical recording and reproducing system having an optical detecting device. The circuit includes a wobble clock recoverer which detects a wobble clock signal from the sum of a sum signal and a push-pull signal of radially half-divided output signals of the optical detecting device, a phase demodulator which provides an output signal having an original signal component and a harmonic component by multiplying the push-pull signal by the wobble clock signal, and a demultiplexer which low pass filters the harmonic component of the output signal and demultiplexes the original signal component to recover land and groove address information.
The present invention also provides a recording medium employing a groove and land recording method, on which recording medium a simple wobble carrier and wobble address information are alternately recorded on both walls of either of a groove track and a land track, the wobble address information being phase modulated with two phases having the maximum possible phase difference therebetween using the simple wobble carrier, and the simple wobble carrier is recorded in a section of an adjacent track corresponding to a section in which the wobble address information is recorded in a current track.